rm subshell usage in docker-php-ext-install for Alpine (#322)

docker-php-ext-install

@@ -90,7 +90,6 @@ if [ "$pm" = 'apk' ]; then
 fi
 
 for ext in $exts; do
-	(
 		cd "$ext"
 		[ -e Makefile ] || docker-php-ext-configure "$ext"
 		make -j"$j"
@@ -101,7 +100,7 @@ for ext in $exts; do
 			-exec basename '{}' ';' \
 				| xargs -r docker-php-ext-enable
 		make -j"$j" clean
-	)
+		cd ..
 done
 
 if [ "$pm" = 'apk' ] && [ -n "$apkDel" ]; then